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01-16-2017, 01:11 PM | #1 |
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Traction control issue...
So about a month ago I replaced the rear tires which, predictably, were wearing about twice as fast as the fronts. Had an alignment done at the same time. Ever since then the DTC (or the DSC, it's hard to tell which as apparently they both use the same dash icon) has been tripping at fairly docile cornering speeds, particularly on sweeping right hand freeway off-ramps. Any ideas as to why the system would be more sensitive now with new rubber on the rear (fronts are half worn)?
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01-16-2017, 05:16 PM | #2 |
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Sounds like they gave you a more positive camber and you're losing traction as a result. Do you have the alignment printout to see if they put you in the proper range?
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01-16-2017, 06:00 PM | #3 |
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It's in spec, but they did go more positive in the rear at my request as I was getting unacceptable inside shoulder wear on the right side.
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01-16-2017, 07:47 PM | #4 | |
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Quote:
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2012 Z4 35i, ED 2/24/2012, Melbourne Red Metallic, Black Leather, Carbon Trim, 6MT, M Sport, CW, PP, PS, NAV, CA. |
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01-16-2017, 11:08 PM | #5 |
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Thanks for the insight. I will meet with the shop foreman for a test drive tomorrow and will raise the issue with him. There shouldn't be a problem as the service advisor was the one who suggested the change and I went along with it. He was trying to be helpful; mistakes happen.
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01-17-2017, 02:17 PM | #6 | |
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I am at ~ -1 in the front and -2.2 in the rear It was exactly as you say... I knew my tires were ready but that was examining the outside/center part of the tire. When I took them off and got a real good look, one of them was down to the cord on the inside! |
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01-17-2017, 03:32 PM | #7 |
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-2'.2" is the kind of negative camber that will cause inner tire wear. I just checked the history of mine. At 29k miles the rears were both set at -2"06" and -2"17" (L/R). When I had the new rear tires installed and the alignment done last month at 42k miles, the left rear was -2'15" and the right rear was -1'56". It was the left rear that had the inner shoulder wear. So at that time the rears were reset -1'27"/-1'28". This, I was told, was the least amount of negative camber they recommended and would help with tire wear. The fronts have been maintained at about -0'50", which seems to work OK. The dealer and I are currently having a discussion over these settings.
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01-18-2017, 08:42 AM | #8 |
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well i experienced this too when i tried to replace just my rears. The explanation that i got was that since there is a dramatic difference between front and rears now that the computer thinks it is slipping when in fact it is not. thus the DSC light on the dash comes one. Once i replaced the fronts too that went away.
I also wrote an article a while back when i experienced this issue but it had to do with a loose condition that existed after replacing just the rear tires. It is amazing how sensitive these vehicles are really to tires.
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01-18-2017, 11:57 AM | #9 | |
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01-18-2017, 01:23 PM | #10 |
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Differing Tire Compounds maybe? I also had that issue where a new set of the exact same tire was not made with the same compound. I had to go back to the tire store and have them research as to why i was having trouble and they finally came across an article that stated the tire was made differently that previous models so that it could be used on the Mercedes brands too. It actually had a MB designation so when we checked the tires that were installed we saw the mb designation. That was when i switched brands to the Continental brand that i have now.
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01-21-2017, 05:25 PM | #11 |
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So I think I finally got to the bottom of this issue. I spent some time with the dealer shop foreman today who first recalibrated the steering angle sensor before we went for a test drive. Took the car through a sweeping right hand uphill freeway off ramp which has caused the DSC/DTC to trigger numerous times recently and got it to do it three times in one traverse! Once at the entrance, once halfway through and once at the exit. On the way back, we talked about the rear camber settings and he claimed they have used these settings before to help with inside tire wear and never had any issues. And at -1.25 degrees, by normal (non-BMW) standards, there's still plenty of negative camber. When we got back to the dealership, he pulled up BMW's specs for front/rear tread depth differential limits and the documentation stated no more than 2-3mm difference with the deeper tread always on the rear of the car. So my new tires are on the rear, but the fronts have 3mm less tread, so I'm right on the ragged edge. That would explain why the problem manifests itself on long sweepers where the system has plenty of time to calculate the differential in tire diameter and interpret it as a symptom of tire slippage, thus triggering the DTC. It never occurs around town even when pushed hard around corners, as the system can't react that quickly to the diameter difference. Long story short, the solution for now is to turn off the DSC when it becomes troublesome and wait for the rears (with their faster wear rate) to close the gap on the fronts dimensionally so the system doesn't get so easily confused. Conclusion: Staggered wheel/tire setups are a PITA!
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01-21-2017, 06:12 PM | #12 |
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Interesting topic. Is this the case of never touching alignment unless it's srsly out of whack? I wonder if anyone experienced improvements after having it done; all I hear are stories like OP's.
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01-21-2017, 07:29 PM | #13 |
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On the contrary. My experience to date is that it easily gets out of whack and it's important to stay on top of it (ie: keep tabs on tire wear)!
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01-21-2017, 08:16 PM | #14 |
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01-27-2017, 03:57 AM | #15 | |
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Unless OP is hitting a lot of potholes the alignment shouldnt change in between setups. I think the issue is lesser grip from less negative camber, and the tires might be made with a mold release lubricant which makes it a bit more slippery when new |
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